1.Introduction

The first BOOTES robotic astronomical station (dubbed BOOTES-1 since 1998) was located at INTA's Estación de Sondeos Atmosféricos in Centro de Experimentación de El Arenosillo, a dark-sky site near Mazagón (Huelva), center owned by the Instituto Nacional de Técnica Aerospacial (INTA). The second observing station was opened in 2001 and it is located at the Estación Experimental de La Mayora (dubbed BOOTES-2), 240 kms apart. The latter is run by the Consejo Superior de Investigaciones Científicas (CSIC).

Figure: The location of the first two BOOTES observing stations in South Spain

2.The Wide Field Cameras (1998-2004)

Commercial Nikkor 50-mm wide-field lenses have been used, attached to two ST8 SBIG CCD cameras, similarly to the Optical Transiend Monitor (OTM) that was in operation at the Astronomical Institute in Ondrejov.

Each pair of the BOOTES wide-field cameras was mounted atop the 0.3-m LX 200 Meade telescope, allowing long integrations of a previously selected region. The four cameras monitor the same region of the sky, both in the I and V-bands. At the proposed locations, typical limiting magnitude is V = 12 for an integration time of 30 s, and V = 14 for 300 s.

Figure: One of the first images obtained by the BOOTE S-1 wide field camera covering the BATSE error box for GRB 980808, taken 66-min after the event.

The system is based on the digital signal processor board Photomate 20 Signal Processor Board which consists of two TMS320C40 processors operated by commercial PCs. The frames taken at each station at the very beginning the night will be loaded into memory (the primary frames). During the rest of the night, sucessive frames (secondary frames) could be compared with the primary frame.

If a real flash were detected in the secondary frames, the coordinates of the flashing object and the images themselves would be transferred to LAEFF-INTA. If the flash were indeed of cosmic origin, an object at an identical position should have also had been recorded in the second twin station. Hence such a configuration will allow to distinguish flashing objects closer than 1 million kms, therefore ruling out satellite glints and another atmospheric and near space background.

Exceptionally, when information on a GRB position would be obtained from the GCN (the GRB Coordinates Network), the cameras used to provide images of the corresponding GRB error boxes. In fact, such capability is proven to be very useful on the basis of the large size of GRB error boxes monitored in Ondrejov.

3.Telescopes

3.1. The 0.2-m telescope (1998-2000)

The first telescope installed in Bootes-1 in 1998 was based at the Burst Alert Robotic Telescope (BART), and used commercially available hardware components. On the basis of positional information of GRBs obtained by means of the Internet network, BOOTES was able to perform rapid follow-up observations of events detected by BeppoSAX and RossiXTE satellites.The telescope were designed to react inmediately (within 1 minute) in order to take unfiltered frames at the position of GRBs detected by the above mentioned satellites.

3.2. The two 0.3-m SC telescopes (2001)

Similarly to the 0.2m telescopes, the 0.3m telescopes were also designed to react inmediately (within 1 minute) in order to take frames (unfiltered, but also in VRI-filters) at the position of GRBs detected by BeppoSAX, RossiXTE, HETE-2, INTEGRAL and SWIFT. Achieved limiting magnitudes were 18.

3.3. The fast slewing 0.6-m RC telescopes (2009)

Similarly to the 0.3m telescopes, the 0.6m telescopes were also designed to react inmediately (within 10 seconds) in order to take frames (unfiltered, g'r'i'Z Y-filters) at the position of GRBs detected by INTEGRAL, SWIFT and FERMI. EEMCCD devices secure the state-of-the-art imaging allowing to reach 20.5 limiting magnitude.

4.Spectrographs

4.1. The wide field spectrograph (2000-2002)

During the Autumn 1999 we designed an instrument capable of obtaining GRB spectra for our rapid response system. When placed on the Cassegrain focus of the 0.3m telescope it is capable of of acquiring slitless spectra of all the objects in a field of 43'x28'. This instrument allows us to have a rapid pointin and fast switching from image to spectroscopic mode. It received first light on November 2000.

Technical information:

Field of View (0.3 f/10 telescope):

43' x 28'

Dispersing element

Direct vision prism

Dispersion :

~4Å/pixel at 4000Å

~30Å/pixel at 5500Å

~100Å/pixel at 8000Å

Limiting magnitude:

13.5 in 30s (spectrographic mode)

Pictures of the instrument mounted on the Cassegrain focus of the 0.3m telescope:

Images obtained through the instrument:

Direct image

Same field with the dispersing element in the optical path

In these images we can see the field surrounding the planetary nebula M57 (ring nebula) in Lyra.

The nebula has two emissions due to ionized hidrogenof which its composed.

We can also see some absorption lines in the stellar objects of the field.

4.2. The COLORES long-slit spectrograph (2011)

A long-slit spectrograph (COLORES) was developed at IAA-CSIC in collaboration with ASU-CAS and got first light in 2011).

5. The software for BOOTES

5.1. A modular software (1998-2004)

5.1.1. Simultaneous and quasi-simultaneous observations of the GRB error boxes detected by satellites